CVE-2026-9545

EUVD-2026-41493
In this scenario, libcurl first uses a proper HTTP/3 server for the initial
transfers, and when it makes a second transfer to the same site it has been
replaced by the attacker's impostor machine - without a valid certificate.

When libcurl returns to the hostname the second time with a cached SSL session
(`CURLOPT_SSL_SESSIONID_CACHE` is not disabled) and early data enabled (the
`CURLSSLOPT_EARLYDATA` bit is set in `CURLOPT_SSL_OPTIONS`), libcurl might
send off the second request's bytes on that new connection *before* enforcing
the certificate verification failure. Potentially leaking sensitive
information.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
curlCNA
7.5 HIGH
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 19.03%
Affected Products (NVD)
VendorProductVersion
haxxcurl
8.11.0 ≤
𝑥
< 8.21.0
𝑥
= Vulnerable software versions
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
curlcurl
𝑥
≤ 8.20.0
CNA
curlcurl
𝑥
≤ 8.19.0
CNA
curlcurl
𝑥
≤ 8.18.0
CNA
curlcurl
𝑥
≤ 8.17.0
CNA
curlcurl
𝑥
≤ 8.16.0
CNA
curlcurl
𝑥
≤ 8.15.0
CNA
curlcurl
𝑥
≤ 8.14.1
CNA
curlcurl
𝑥
≤ 8.14.0
CNA
curlcurl
𝑥
≤ 8.13.0
CNA
curlcurl
𝑥
≤ 8.12.1
CNA
curlcurl
𝑥
≤ 8.12.0
CNA
curlcurl
𝑥
≤ 8.11.1
CNA
curlcurl
𝑥
≤ 8.11.0
CNA
Debian logo
Debian Releases
Debian Product
Codename
curl
bookworm
7.88.1-10+deb12u15
fixed
bookworm (security)
7.88.1-10+deb12u5
fixed
bullseye
7.74.0-1.3+deb11u13
fixed
bullseye (security)
7.74.0-1.3+deb11u16
fixed
forky
8.21.0-2
fixed
sid
8.21.0-2
fixed
trixie
no-dsa
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
curl
bionic
not-affected
focal
not-affected
jammy
not-affected
noble
not-affected
questing
Fixed 8.14.1-2ubuntu1.4
released
resolute
Fixed 8.18.0-1ubuntu2.2
released
trusty
not-affected
xenial
not-affected
openSUSE logo
openSUSE / SLES Releases
openSUSE Product
Release
curl
suse enterprise desktop 15 SP7
8.14.1-150700.7.20.1
fixed
suse enterprise sap 15 SP4
8.14.1-150400.5.86.1
fixed
suse enterprise sap 15 SP5
8.14.1-150400.5.86.1
fixed
suse enterprise sap 15 SP7
8.14.1-150700.7.20.1
fixed
suse enterprise server 15 SP4
8.14.1-150400.5.86.1
fixed
suse enterprise server 15 SP5
8.14.1-150400.5.86.1
fixed
suse enterprise server 15 SP6
8.14.1-150600.4.46.1
fixed
suse enterprise server 15 SP7
8.14.1-150700.7.20.1
fixed
libcurl-devel
suse enterprise desktop 15 SP7
8.14.1-150700.7.20.1
fixed
suse enterprise sap 15 SP4
8.14.1-150400.5.86.1
fixed
suse enterprise sap 15 SP5
8.14.1-150400.5.86.1
fixed
suse enterprise sap 15 SP7
8.14.1-150700.7.20.1
fixed
suse enterprise server 15 SP4
8.14.1-150400.5.86.1
fixed
suse enterprise server 15 SP5
8.14.1-150400.5.86.1
fixed
suse enterprise server 15 SP6
8.14.1-150600.4.46.1
fixed
suse enterprise server 15 SP7
8.14.1-150700.7.20.1
fixed
libcurl4
suse enterprise desktop 15 SP7
8.14.1-150700.7.20.1
fixed
suse enterprise sap 15 SP4
8.14.1-150400.5.86.1
fixed
suse enterprise sap 15 SP5
8.14.1-150400.5.86.1
fixed
suse enterprise sap 15 SP7
8.14.1-150700.7.20.1
fixed
suse enterprise server 15 SP4
8.14.1-150400.5.86.1
fixed
suse enterprise server 15 SP5
8.14.1-150400.5.86.1
fixed
suse enterprise server 15 SP6
8.14.1-150600.4.46.1
fixed
suse enterprise server 15 SP7
8.14.1-150700.7.20.1
fixed
libcurl4-32bit
suse enterprise desktop 15 SP7
8.14.1-150700.7.20.1
fixed
suse enterprise sap 15 SP4
8.14.1-150400.5.86.1
fixed
suse enterprise sap 15 SP5
8.14.1-150400.5.86.1
fixed
suse enterprise sap 15 SP7
8.14.1-150700.7.20.1
fixed
suse enterprise server 15 SP4
8.14.1-150400.5.86.1
fixed
suse enterprise server 15 SP5
8.14.1-150400.5.86.1
fixed
suse enterprise server 15 SP6
8.14.1-150600.4.46.1
fixed
suse enterprise server 15 SP7
8.14.1-150700.7.20.1
fixed